document.write( "Question 1123419: if two vertices of an equilateral triangle are (-4,-3) and(4,1), find the remaining vertex\r
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Algebra.Com's Answer #739738 by math_helper(2461)\"\" \"About 
You can put this solution on YOUR website!
There are two solutions (corresponding to points C and D) as shown in the drawing below. \r
\n" ); document.write( "\n" ); document.write( "Line AB has the equation \"+y+=+%281%2F2%29x+-+1+\"
\n" ); document.write( "Line CD has the equation \"+y+=+-2x+-+1+\"\r
\n" ); document.write( "\n" ); document.write( "\"+abs%28AB%29%5E2+=+%284-%28-4%29%29%5E2+%2B+%281-%28-3%29%29%5E2+=+64%2B16+=+80+\"\r
\n" ); document.write( "\n" ); document.write( "Using point C(Cx, Cy), the distance squared to C from B (and A) must be 80. Using B's coordinates:
\n" ); document.write( "\"+%28Cx-4%29%5E2+%2B+%28Cy-1%29%5E2+=+80+\"
\n" ); document.write( "\"++%28Cx%5E2-8Cx%2B16%29+%2B+%28Cy%5E2-2Cy%2B1%29+=+80+\"
\n" ); document.write( "Subs \"+Cy+=+-2Cx+-+1+\" and \"Cy%5E2+=+4Cx%5E2+%2B+4Cx+%2B1\" :
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\n" ); document.write( "\"+%28Cx%5E2-8Cx%2B16%29+%2B+%284Cx%5E2%2B4Cx%2B1%29+%2B+%284Cx+%2B+2%29+%2B+1+=+80+\"\r
\n" ); document.write( "\n" ); document.write( "Which resolves to C at ( \"2%2Asqrt%283%29+\" , \"+%28-4%2Asqrt%283%29%29-1++\" )
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\n" ); document.write( "\n" ); document.write( "and D at ( \"-2%2Asqrt%283%29+\" , \"+%284%2Asqrt%283%29%29-1++\" )
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